Question

int main(void) {
    char *input;
    printf("prompt>");
    scanf("%s", input);
    printf("%s", input);
    return 0;
}

prompt>input

RUN FAILED (exit value 138, total time: 3s)

What’s wrong with the code? Has to be either the scanf() or the second printf(). The input is of unknown length. A lot people have said to simply create a char array of length ‘X’ to hold the input. Just wanted to know then why this code works.

#include <stdio.h>
#include <stdlib.h>

int main(void) {
    /* prompt */
    char input;
    printf("prompt>");
    scanf("%s", &input);
    printf("%s", &input);
    return 0;
}

Answer 1

  char *input;

Is only a pointer – there is no data space allocated store the data that scanf collects.

try this instead

char input[100];